Prevent some view controller in a navigation controller from rotating

Question

I have a navigation controller which displays two view controllers at once. They are layered and the front most controller can be dragged down to reveal the controller below. My app delegate is configured so the app will only allow interface orientations when the view in the back is being revealed, as seen below.

- (NSUInteger)application:(UIApplication *)application supportedInterfaceOrientationsForWindow:(UIWindow *)window
{
    if (self.revealNavigationController.isViewRevealed)
    {
        return UIInterfaceOrientationMaskAllButUpsideDown;
    }

    return UIInterfaceOrientationMaskPortrait;
}

Naturally this causes both the front and the back view controller to rotate when the device is rotated but I am only interested in rotating the back view controller. Is there any way to completely disable rotation in the front most view controller?

Answer 1

The solution suggested by axiixc is generally better so depending on your problem, you should look at his answer. However, this did not solve my problem. I had a UINavigationController in which I inserted the view of a view controller as subview at index 0. This way, the view would be in the back. I had then made the UINavigationBar draggable so that when it dragged down, it would reveal the view in the back. The front most view would then move with the navigation bar. I did not manage to get this to work with the view controller containment API introduced iOS 5, as suggested by axiixc.

Instead, I removed the view from the navigation controller and added it directly to the UIWindow when the app was launched and I handled the rotation of this view myself and disabled rotation on all other views (that is, I disabled it on the navigation controller).

This is how I added the view in -application:didFinishLaunchingWithOptions:

self.revealViewController = [[RevealViewController alloc] init];
[self.window insertSubview:self.revealViewController.view atIndex:0];

Then, right after that I registered for UIDeviceOrientationDidChangeNotification.

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(didRotate:) name:UIDeviceOrientationDidChangeNotification object:nil];

My didRotate: looks like this: (this is inspired by another answer on StackOverflow which I am now unable to find again, sorry)

- (void)didRotate:(NSNotification *)notification
{
    // Only rotate if the view is revealed
    if (self.revealNavigationController.isViewRevealed)
    {
        UIDeviceOrientation orientation = [UIDevice currentDevice].orientation;
        [self updateForDeviceOrientation:orientation animated:YES];
    }
}

I call -updateForDeviceOrientation:animated:

- (void)updateForDeviceOrientation:(UIDeviceOrientation)orientation animated:(BOOL)animated
{
    CGFloat degrees = 0.0f;
    switch (orientation)
    {
        case UIDeviceOrientationLandscapeLeft:
            degrees = 90.0f;
            break;
        case UIDeviceOrientationLandscapeRight:
            degrees = -90.0f;
            break;
        case UIDeviceOrientationPortrait:
            degrees = 0.0f;
            break;
        default:
            break;
    }

    CGFloat duration = (animated) ? [UIApplication sharedApplication].statusBarOrientationAnimationDuration : 0.0f;

    __weak typeof(self) weakSelf = self;
    [UIView animateWithDuration:duration animations:^{
        // Rotate view
        weakSelf.revealViewController.view.transform = CGAffineTransformIdentity;
        weakSelf.revealViewController.view.transform = CGAffineTransformMakeRotation(DEGREES_TO_RADIANS(degrees));

        // Resize view for rotation
        CGFloat width, height;
        if (UIDeviceOrientationIsLandscape(orientation))
        {
            width = MAX(CGRectGetWidth(weakSelf.revealViewController.view.bounds), CGRectGetHeight(weakSelf.revealViewController.view.bounds));
            height = MIN(CGRectGetWidth(weakSelf.revealViewController.view.bounds), CGRectGetHeight(weakSelf.revealViewController.view.bounds));
        }
        else
        {
            width = MIN(CGRectGetWidth(weakSelf.revealViewController.view.bounds), CGRectGetHeight(weakSelf.revealViewController.view.bounds));
            height = MAX(CGRectGetWidth(weakSelf.revealViewController.view.bounds), CGRectGetHeight(weakSelf.revealViewController.view.bounds));
        }

        CGSize newSize = CGSizeMake(width, height);

        CGRect viewBounds = weakSelf.revealViewController.view.bounds;
        viewBounds.size = newSize;
        weakSelf.revealViewController.view.bounds = viewBounds;

        CGRect viewFrame = weakSelf.revealViewController.view.frame;
        viewFrame.size = newSize;
        weakSelf.revealViewController.view.bounds = viewFrame;
    }];
}

Answer 2

You need to use the view controller containment APIs added in iOS5. Basically, what you need to do is remove your one view controller when you no longer want it to participate in the rotation events, and add it back when its ready again. A sample would be...

@implementation AXRotationDemoViewController

- (id)init
{
    if ((self = [super init]))
    {
        self.oneViewController = [[AXLoggingViewController alloc] init];
        self.oneViewController.interfaceOrientations = UIInterfaceOrientationMaskPortrait;

        self.twoViewController = [[AXLoggingViewController alloc] init];
        self.twoViewController.interfaceOrientations = UIInterfaceOrientationMaskAllButUpsideDown;
    }

    return self;
}

- (void)viewDidLoad
{
    [self.oneViewController willMoveToParentViewController:self];
    [self addChildViewController:self.oneViewController];
    [self.view addSubview:self.oneViewController.view];
    [self.oneViewController didMoveToParentViewController:self];

    [self.twoViewController willMoveToParentViewController:self];
    [self addChildViewController:self.twoViewController];
    [self.view addSubview:self.twoViewController.view];
    [self.twoViewController didMoveToParentViewController:self];

    self.oneViewController.view.backgroundColor = [UIColor redColor];
    self.twoViewController.view.backgroundColor = [UIColor greenColor];

    UIButton * showBackButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    [showBackButton setTitle:@"Toggle Back/Front" forState:UIControlStateNormal];
    [showBackButton addTarget:self action:@selector(_toggle:) forControlEvents:UIControlEventTouchUpInside];
    [showBackButton sizeToFit];
    showBackButton.center = self.view.center;
    [self.view addSubview:showBackButton];
}

- (void)_toggle:(id)sender
{
    if ([self.childViewControllers containsObject:self.oneViewController])
    {
        [self.oneViewController.view removeFromSuperview];
        [self.oneViewController removeFromParentViewController];
    }
    else
    {
        [self.oneViewController willMoveToParentViewController:self];
        [self addChildViewController:self.oneViewController];
        [self.view addSubview:self.oneViewController.view];
        [self.oneViewController didMoveToParentViewController:self];

        UIWindow * window = self.view.window;
        UIViewController * hack = window.rootViewController;
        window.rootViewController = nil;
        window.rootViewController = hack;
    }
}

- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];

    CGRect halfScreenFrame = self.view.bounds;
    halfScreenFrame.size.height /= 2;

    self.oneViewController.view.frame = halfScreenFrame;
    self.twoViewController.view.frame = CGRectOffset(halfScreenFrame, 0, halfScreenFrame.size.height);
}

- (NSUInteger)supportedInterfaceOrientations
{
    if ([self.childViewControllers containsObject:self.oneViewController])
        return self.oneViewController.supportedInterfaceOrientations;

    return self.twoViewController.supportedInterfaceOrientations;
}

@end

However you may notice, there is no official way to really tell iOS you've changed the value of supportedInterfaceOrientations, so your best bet is either a) use a hack like in my example above to force iOS to redo everything or b) don't let the user close the back view until the device is already in portrait again.

Here is the sample I put together if that doesn't explain things well enough.

Answer 3

Yes, take a look at the -supportedInterfaceOrientations method in UIViewController. You return a UIInterfaceOrientationMask bitmask that specifies the orientations you want that UIViewController subclass to support.